1. Field of Invention
The present invention relates to a quick coupler for coupling a tool such as an excavator bucket, a clamshell grapple or demolition shears to a tool operator such as an excavator arm or the like, comprising a coupling mount for receiving a first locking part and a locking mount for receiving a second locking part, wherein a locking element for locking the second locking part in the locking mount is at least associated with the locking mount, with the locking element being actuable by an adjustment actuator.
2. Background and Related Art
Quick couplers are frequently used with construction machines such as hydraulic excavators or articulated grippers such as wood handling machines or demolition units or similar material transfer machinery for coupling different tools such as rakers, clamshell grapples or demolition shears to an excavator arm or similar tool operators such as articulated arm booms in order to be able to use different tools without long changeover times.
Such quick couplers can in particular have two mutually spaced apart locking axles as locking elements at a coupling part, whereas the other coupling part, in particular the coupling part at the excavator arm side, can have a preferably hook-shaped coupling mount for hooking at a first one of the two locking axles and a locking mount for locking at the second locking axle. After hooking the first locking axle in the coupling mount, the two coupling parts can be pivoted with respect to one another, wherein the locking axle seated in the coupling mount forms the pivot axle so that the second locking axle moves or is pivoted into the locking mount where the second locking axle can then be locked by a locking element such as an extendable wedge so that it is simultaneously also no longer possible to move the first locking axle out of the coupling mount. An adjustment actuator that is actuated by outside energy and that can, for example, be configured as a hydraulic cylinder and can typically be actuated by hydraulic pressure from the unit is provided to move the locking element.
The locking axles at the one coupling part can in this respect be formed by locking pins which can extend at the corresponding coupling part, in particular in parallel with one another, with optionally instead of such pins also other structural parts of the coupling part such as projecting noses, axle pivots, engagement stubs in the form of projections or recesses, for example in the form of pockets, being able to serve as the locking part, however, and being shape-matched to the coupling mount or to the locking mount of the other coupling part.
It has already been proposed for the prevention of the first locking axle from being released from the coupling mount again on the pivot process after the hooking of the first locking axle into the coupling mount also to associate a securing element, for example in the form of a spring-loaded snap-in wedge, to the coupling mount, with the snap-in wedge capturing the locking axle on the hooking of the locking axle into the coupling mount and securing it in the coupling mount. On the moving of the locking axle into the coupling mount, the securing snap lock is pressed back until the completely hooked-in position is reached so that the securing snap lock can snap back again and can block the exit path from the coupling mount. To be able also to move the first locking axle or to unhook it from the coupling mount on the removal of a tool after the unlocking of the locking mount, this securing element can be released again by a further adjustment actuator or can be moved into its releasing position again. This can take place with pressure medium actuation, for example by a simply acting pressure medium cylinder which can move the securing element back into the releasing position against its spring pre-loading into the locking or blocking position. A climbing down of the machine operator or a manual actuation can hereby be avoided.
To be able to actuate the locking and securing elements independently, it is possible to work with mutually decoupled, separate pressure circuits for the actuation of the locking mechanism and the unlocking of the securing element at the coupling mount, which EP 1 852 555 A2 shows, for example. In this respect, however, three pressure lines are as a rule required that are led along the excavator arm to the quick coupler, which in particular requires a corresponding, very expensive retrofitting with older units.
Since in practice in the past quick couplers of the named type, which were sold in large volumes and which are still in use today, were/are not provided with such an additional securing element at the coupling mount, it would be desirable not only to provide such an additional securing means at the coupling mount with new devices, i.e. new quick couplers, but also to be able to retrofit them to old quick couplers. The solution shown in EP 1 852 555 A2 is admittedly generally also suitable for retrofitting already existing quick couplers, but it requires three hydraulic connections due to the separate pressure circuit for actuating the securing element of the coupling mount, namely two connections for actuating the actual locking mechanism and a further pressure connection for unlocking the securing element of the coupling mount. In many cases, however, only two hydraulic connections are present at existing devices so that the retrofitting with such an additional security at the coupling mount is often not possible.
In order also to enable an additional security which is easy to actuate with only one pressure medium circuit and with a limited number of pressure medium connectors, it is proposed in DE 20 2012 007 124 U1 to connect the additional securing element via a pressure switch valve to the pressure circuit that is provided for the actuation of the main locking element. The pressure circuit can in this respect be ramped up to an increased pressure level by bypassing a pressure reducing valve, at which increased pressure level the pressure switch valve opens so that the additional security can be released against its spring pre-load. It is additionally proposed in DE 20 2014 001 328 U1 to use a dual-action cylinder instead of a single-action adjustment cylinder as the adjustment actuator in order hereby to avoid the spring pre-load of the securing element and also to be able to enforce a locking by hydraulic pressure even on difficult motion as a consequence, for example, of contamination.
DE 20 2012 007 124 and DE 20 2014 001 328 U1 admittedly avoid the problem of having to attach a third hydraulic line to the excavator arm; however, they require a sufficiently high hydraulic pressure from the excavator side or from the carrier unit side that is not always provided by the carrier unit or that requires corresponding interventions in the hydraulic system of the carrier unit. To be able to provide the required pressure, the pump at the carrier unit has to be pivoted outward sufficiently far, for which purpose the control of a different hydraulic function of the carrier unit is required at times, in particular when the quick coupler is retrofitted and was not yet taken into account in the original hydraulic control of the carrier unit. The bucket cylinder is, for example, traveled outwardly at times to have sufficient pressure for the actuation of the quick coupler and its locking element.
The issue that the hydraulic system at the carrier side at times only provides the pressure required for the quick coupler by special interventions relates per se not only to quick couplers in which both a securing element is associated with the coupling mount and a latching element is associated with the locking mount and the securing and locking elements have to be actuated after one another, but rather also applies to simpler quick couplers in which only one locking element has to be locked or unlocked.
Starting from this, it is the underlying object of the present invention to provide an improved quick coupler of the kind that avoids disadvantages of the prior art and further develops the latter in an advantageous manner. A simply designed lock should in particular be provided that can be actuated securely in the long term, that does not need any increased number of pressure medium connections and that also does not require any special demands and interventions at or in the hydraulic system.